750 qf vac sec running rich

Manual or electric choke? If manual, wire it open and verify your air cleaner isn't messing with it. If electrical, make sure it has power and is opening fully. I've seen the linkages for the choke be bound, so look it over and be sure it's all free. How is your PCV set up? Also be sure your throttle cable isn't allowing the blade to shut all the way.